The conventional floor material with a heater contained therein, as described later with reference to the drawings, comprises for example a plywood, on which a light weight cement layer is formed, a heater wire meanderingly arranged on said light weight cement layer, a metallic plate laminated on said plywood and a dressed sheet laminated on said metallic plate, both end of said heater wire being connected to an electrode. Such the floor materials with a heater contained therein are stood in a row by putting convex portions formed in an edge portion of one floor material in concave portions formed in an edge portion of another floor material and placed on floor joints fixedly mounted on support woods by means of nails and the like.
The floor materials with a heater contained therein having such the conventional construction are stored under the condition that the plywood, the dessed sheet and the like are unificated, so that many kinds of floor materials must be prepared depending upon the kind of dressed sheets, the change in total thickness, the change in area and the like. This is economically disadvatageous and can not meet an order for a large quantity of products of single kind.
In addition, with the above described conventional construction, a problem occurs in that merely the circumference of the heater wire, which is meanderingly arranged, is heated, that is, the local heating is brought about to produce the low temperature burn. Furthermore, the heating operation can not be expected by the breakage of merely one place of the heater wire. Accordingly, such floor materials can not be used for the heating when they are cut for the adjustment to an indoor size. In addition, in order to obtaIn a sufficient heat insulating temperature, the corresponding high electric current is required. That is to say, a problem occurs also in that when a weak point exists in a heating portion such as heater wire, the heating portion is broken to make an arc due to a short-circuit thereby firing.
Besides, with the above described conventional construction, the floor material with a heater contained therein is heated by electrifying the heater wire but the plywood is dried with the lapse of time when it is used to produce the shrinkage thereby producing a gap between it and the floor joints or gaps between the concave portions and the convex portions. As a result, the creak is generated when persons walk on the floor materials. In addition, the edge portion of the dressed sheet is gotten turned up due to the shrinkage to lead to the possibility that persons' feet are caught by the edge portion of the dressed sheet to injure the persons.